IPT Notes
A guide to the Term 1 IPT test. =Introducing Systems= Systems and their environment System: '''A collection of parts that work together to achieve a particular purpose or result. '''Information System: '''Accepts data as an input and produces information or processed data as an output. Performs a set of information processes requiring participants, data/information and information technology. '''Information Technology: '''the equipment (hardware) used by an information system and the instructions (software) that control the equipment. Information systems involve: · Information technology · Data/information · Processes · Participants '''Participant: anyone who is involved in the operation or running of an information system. Every system has a purpose that describes why it is needed. Environment: '''where an information system is used. Includes everything that influences or is influenced by an information system and its purpose. IT includes any other systems that supply data (inputs) and accept data/information (outputs) from the system. Information systems depend on their environment for their data. Information systems can have an effect on their environment. Systems, purpose & people Many information systems are specifically designed for just one particular task. The home pc is a general information system. '''General information system: Systems capable of performing a wider variety of information tasks. The success of computer-based information systems is due to the development of newer and faster technologies. Improved information systems have led to greater needs and higher expectations. End user: 'Receives the data/information produced by an information system. A personal information system normally has only one participant. The end users have total control over a personal information system. A group information system shares data/information with many participants. Individual users usually have little control in a group information system. =Data, information and processes= Systems and data '''Binary: '''A number system that uses two digits, 0 and 1, to represent all possible values. '''Bit: '''the smallest unit of data. It is a single binary digit, a 0 or a 1. '''Byte: '''the smallest useful unit of data. It consists of 8 individual bits. Digital technology provides use with faster and more reliable information. Data from the real world have to be converted to digital. The five types of data are text, numerical, image, audio and video. '''Text: '''A sequence of symbols used in a natural or artificial language. English is a natural language, while the languages used to program computers are artificial languages. Text is the simplest type of data. Text data are represented by numerical values. ASCII code is one of the best known and most widely used codes to represent text. '''Numerical data: '''represent pure numbers, such as measurements and calculation results. Numerical data is easily stored as binary data. Bytes can be combined into ‘words’ to represent large numbers. 255 is the largest number that can be stored on a single byte. 65535 on 2 bytes and 4294967295 on 4 byte '''Image: '''an electronic copy of a picture, page, scanned document or other object for display on a screen or paper. '''Pixel: '(picture element) the smallest controllable display element on a Visual display unit. '''Bit map: '''a sequence of numerical values representing a sequence of pixels. Can be cropped. Cannot be resized without loss of resolution. '''Vector graphics: uses a few numerical values to represent an entire object, such as a line or geometric shape. Cannot be cropped. Can be resized without loss of resolution. Cannot represent photographs. Audio data: measures the volume and pitch of a sound. Digitising creates digital values from measurements of samples of real world data. Video data: '''A sequence of still images recorded many times a second. Most information systems rely on exchanging data with other systems. The usefulness of data often depends on how the data are presented to users. Systems and processes The collecting process gathers data from the real world environment of an information system. The organising process prepares the data for use by the other information processes The analysing process transforms data into useful information. The storing and retrieving process moves data to or from storage devices The processing process allows data to be updated, altered or edited. The transmitting and receiving process exchanges data/information with other information systems. The displaying process presents users with the output of an information system. Models or diagrams of systems are used to help understand the role of the data processes. '''Context diagram: '''a diagram of an information system that shows the situation or environment where it is used, the sources of its inputs and the destinations of its outputs. '''Data flow diagram: '''A diagram that shows how data move through an information system. The introduction of computer-based information systems has brought up a few social and ethical issues, the main ones being: · Privacy and security – communication technology allows data to be accessed by multiple users. · Access and control – If certain systems such as the internet are shut down many people will lack information. Also, if people can’t afford computers they may lack information that is only distributed through the internet/on computers. · Employment and the changing nature of work – Many jobs replaced by computer information systems. =Tools for collecting= The collecting process '''Collecting: '''the process of gathering data for use by an information system. You have no control over how or where a web search engine collects its data. Original data that you have collected yourself are usually preferred to second-hand data. If on information system sends data to another, then the first information system can be simply described as a ‘data collection process’ Collecting hardware '''Qwerty keyboards have an arrangement of keys named after the sequence of letters formed by the first six alphabetical keys. Alternative keyboard layouts provide specialised data entry features. Spoken text is an alternative to typed text. OCR or optical character recognition uses intelligent software to identify text characters in a bitmapped image. The best OCR systems have an error rate of about 2 characters every 100 scanned. Bar codes have become the standard method for identifying virtually anything. Data loggers: '''Recording devices that can collect and store numerical data for an information system. Numerical data can be collected as text and then converted. Video collecting hardware relies on making many measurements of a video signal. Audio collecting hardware relies on making many measurement samples of sound. Data collection devices are becoming complete information systems on their own. Collecting software When collecting pure text every keystroke is stored using its ASCII value. When collecting text data, some data values may be replaced by others. Data collection and data processing often occur at the same time. Word processors provide tools for repairing collected text. A web browser can be used to collect text data. Software forms an interface between data collection systems and information systems. Spreadsheets are commonly used to collect numerical data. Hardware devices for collecting images need controlling software. A web browser is a software tool for collecting images from the internet. Structured form layouts are designed to reduce data entry errors Social issues Data collection often involves accessing personal and private data. The sources of collected data should be identified. The value of an information system depends on the accuracy of the data it collects. Data collection tools should be tested before being put into use. A well-designed work environment is safer and more productive. '''Ergonomics: '''the study of human factors involved in the design of the workplace. =Tools for organising= The organising process '''Organising: '''the process of arranging, representing and formatting data for use by other information processes. Data preparation organises data for non-display processes. Document preparation organises data for the display process. Text data are usually organised for the display process. Text organised as image data plays an important role on the web. Numerical data can be organised as text data to make the display process easier. Numerical data organised into a spreadsheet format allows for display, analysis and processing by the spreadsheet application. '''Palette: '''the number of colours available for an image. Bit map images are organised using the characteristics of individual pixels. '''Colour table: stores the set of colours in an image palette. Colour tables are only used when an image palette is smaller than the display pallet. RGB: A colour system that mixes different intensities of three colours – red, green and blue – to make a display colour. Each of these colours is stored as a single byte with an intensity value from 0 (off) to 255 (full on). Vector images are organised using the characteristics of individual objects. Compression: 'reduces the quantity of data in an image when it is stored as a file. The method used to compress and then restore an image data file is often called a ‘codec’ for '''Co'mpression/'Dec'ompression. '''Alpha channel: stores additional data (such as the level of transparency) about every pixel in an image. It is a separate data value to the RGB colour values of a pixel. Audio data can be organised as waveform or MIDI. Many audio formats delete some of the collected data measurements to reduce their quantity. MIDI is a popular audio format for music files created by instruments alone. Organising software Text editors are the simplest organising tools for text data. Word processors provide tools for organising text data into documents. WYSIWYG (what you see is what you get): '''displays data in a graphical form that is as close as possible to the appearance of the final printed document. '''Hypertext: '''text organised in such a way that when selected (e.g. clicked with a mouse) new information will be shown. HTML editors and web editors provide tools for organising text data for the web. Desktop publishers provide tools for organising text into documents. Spreadsheet programs provide tools for organising numerical data. The software tools for organising image data are generally called paint (or bitmap) software and draw software applications. Video and animation data require the greatest amount of organisation. '''Key frame: a frame in an animation or video that contains all the image data. The frames that follow the key frame contain only the parts of the image that are different from the image in the key rame. Video data are usually recorded live in a format with little or no compression and later organised into a higher compression format. A database uses tables to organise numerical and text data. Data dictionary: '''a database that describes data. It identifies and organises the data used by information processing systems. Data dictionaries help organise data for information system designers and database users. The variety of different organising formats for a data type creates problems for data sharing. '''Conversion filter: '''a process built into a software application that will change the format of data being loaded or saved by the application. '''Conversion software: '''a utility program that will load a file created in one data format and then save a copy of the file created in one data format and then save a copy of the file in a different data format. Non-computer-based organising tools For home users, paper-based telephone books still offer advantages over the more versatile electronic versions. Most card catalogue systems have been replaced by computer-based systems. Paper-based data forms are still one of the most common ways of organising data. Computer technology has helped overcome some of the problems with paper-based data forms without replacing them. The last few years have seen an enormous growth in digital imaging technologies in both the consumer and personal markets. Printed catalogues will continue to be dropped into your mailbox for some time to come. Social issues The web has turned hypertext into a standard feature on a wide variety of software applications. '''Hypermedia: '''any display object (such as a graphic or text) that can link you to new information. Hypertext is a text-only form of hypermedia. A home computer is now seen as an entertainment and information tool, not just a data processor. Poorly or incorrectly organised data can cause serious problems. '''Redundant data: '''occur where there is more than one copy of the same data in a database. Poorly organised data that describe dates can lead to confusion. A ‘lazy’ or ‘shortcut’ approach to organising data formats can lead to problems. (e.g. year 2k bug) =Tools for analysing= '''Data: '''raw facts, items that have no meaning or clear purpose '''Information: Data that are meaningful, that have a clear purpose Analysing: The process that transforms data into information. The original data are not altered in the process. The analysing process can use labelling calculations or graphical processes. Data analysis is used for decision making. A large amount of storage space is needed for the analysing process Primary storage: onboard storage devices built into an information system. Such as RAM and ROM. Secondary storage: Means storage devices attached to an information system such as hard drives. The analysing process us improved by the use of fast processors. 'Data bus: '''the ‘bus’ consists of the wires that allow data to enter and leave the CPU. The bus size controls the number of data bytes that can enter and leave the CPU in a single step. A CPU with a data bus that is 64 bits wide can more 8 bytes of data in or out in one direction '''Clock speed: '''the number of timing signals produced every second by an electronic clock on the system motherboard or in the CPU. The signals are used to control the operation of the CPU. A CPU that operates with a clock speed of 2GHz (2 bill clock pulses every second) will obey twice as many instructions in a second as a CPU with a clock speed of 1GHz '''Flop rating: '''A ‘FLOP’ ('Fl'oating-point '''Op'eration) indicates how many floating-point numbers (numbers that are used to represent decimals and very large or very small values) can be added together in a second. It is considered to be a more reliable indicator of CPU speed than the clock speed. Working in parallel with other CPUs allows for jobs to be divided between them, speeding up the process. Analysing software Common analysing task is to search data for particular values or patterns. '''Search Key: '''The set of text characters that the analysing process attempts to find in the collected data. Wildcard matches use the symbols ‘?’ and ‘*’ to represent other characters. '''Logical operator: '''allows two or more searches to be combined. Logical operators use the words AND and OR to join searches together. When searching numerical data the numerical value of the search key is compared with the collected data. Image, audio and video data searches are usually based on searching their filenames or file descriptions. '''Sorting: '''puts data into a set order Sorting text data can cause unexpected results. '''Model: '''A description of a system, process or object. '''Simulation: '''Uses a model to predict the behaviour of a system or process. While simulations can be set up on a spreadsheet program, specialised software is often used to provide faster calculations or greater realism. Simulations are only as good as their data and analysing processes. '''What-if analysis: '''Allows a user to make temporary alterations to data to observe the effects on a model. The advantages of charts and graphs over tables are: · Impact · Speed · Simplicity The choice of which chart to use will depend on the type of data being analysed. The number series identifies the number of data sets (columns and/or rows) that are being plotted in the chart. Analysing the differences between data files works best on fixed length files. Non-computer-based analysing tools and social issues People-based data analysing is usually unreliable. Paper-based models are common tolls for analysing information systems. Access to government data for analysis is covered by the freedom of information act. The organisation of census data allows detailed analysis to be performed while preventing unauthorised analysis of personal data. The incorrect analysis of data will often result in poor decision-making. The ability of information systems to link data from different databases is a greater threat to privacy than the individual databases themselves. Category:Useful Page Category:Other